676 research outputs found
Management of Biesboch reservoirs for quality control with special reference to eutrophication
The three Biesbosch Reservoirs are pumped storage reservoirs, fed with rather polluted and highly eutrophic water from the River Meuse. Air injection at the bottom of the reservoirs prevents thermal stratification, which would otherwise result in serious water quality deterioration. Reservoir mixing also serves as an economic algal control measure; mixing over sufficient depth causes light to play the role of limiting factor and this, combined with zooplankton grazing, keeps the biomass of phytoplankton at acceptable levels. Special problems are caused by benthic, geosmin-producing Oscillatoria species growing on the inner embankment. Rooting up the bottom with a harrow is used as the method of control, based on underwater observations by biological staff trained as SCUBA-divers. With regard to pollutant behaviour the three reservoirs act as a series of fully mixed reactors. This enables the application of kinetic models to describe their behaviour and allows the use of a selective intake policy, e.g. for suspended solids with associated contaminants, ammonia and polynuclear aromatic hydrocarbons. A combination of selective intake and self- purification processes - enhanced by the compartmentalisation of the storage volume in three reservoirs - leads to a striking improvement for many water-quality parameters
Rock-eating mycorrhizas: their role in plant nutrition and biogeochemical cycles
A decade ago, tunnels inside mineral grains were found that were likely formed by hyphae of ectomycorrhizal (EcM) fungi. This observation implied that EcM fungi can dissolve mineral grains. The observation raised several questions on the ecology of these ¿rock-eating¿ fungi. This review addresses the roles of these rock-eating EcM associations in plant nutrition, biogeochemical cycles and pedogenesis. Research approaches ranged from molecular to ecosystem level scales. Nutrient deficiencies change EcM seedling exudation patterns of organic anions and thus their potential to mobilise base cations from minerals. This response was fungal species-specific. Some EcM fungi accelerated mineral weathering. While mineral weathering could also increase the concentrations of phytotoxic aluminium in the soil solution, some EcM fungi increase Al tolerance through an enhanced exudation of oxalate. Through their contribution to Al transport, EcM hyphae could be agents in pedogenesis, especially podzolisation. A modelling study indicated that mineral tunnelling is less important than surface weathering by EcM fungi. With both processes taken together, the contribution of EcM fungi to weathering may be significant. In the field vertical niche differentiation of EcM fungi was shown for EcM root tips and extraradical mycelium. In the field EcM fungi and tunnel densities were correlated. Our results support a role of rock-eating EcM fungi in plant nutrition and biogeochemical cycles. EcM fungal species-specific differences indicate the need for further research with regard to this variation in functional traits
Solubilization of green plant thylakoid membranes with n-dodecyl-α,D-maltoside. Implications for the structural organization of the Photosystem II, Photosystem I, ATP synthase and cytochrome b6f complexes
Solubilization of green plant thylakoid membranes with n-dodecyl-α,D-maltoside. Implications for the structural organization of the Photosystem II, Photosystem I, ATP synthase and cytochrome b6f complexes
Flexible copyright: the law and economics of introducing an open norm in the Netherlands
This study analyses the law and economics of introducing flexibility in the system of exceptions and limitations in Dutch copyright law. Such flexibility would exist in an open norm, on the basis of which the courts can decide whether certain uses of copyrighted material are permissible or not, instead of explicitly defining this in the law. First, it assesses problem areas where the lack of flexibility creates legal disputes and potential barriers to innovation and commercialisation. Second, it analyses the economic rationale and economic effects of introducing flexibility. The study was commissioned by the Dutch Ministry of Economic Affairs, Agriculture & Innovation. Research methods used are literature review and in-depth interviews. The study includes a case study of Israel, where a fair use exception was introduced in the Copyright Act in 2007. Exceptions and limitations in the current copyright system are meant to balance the protection granted to rights owners with the public interest’s need to make certain unauthorized uses. However, this report identified a number of situations that do not fit well within the current set of exceptions and limitations and attributes this to a lack of flexibility. Among these uses are the activities of search engines, the use of works in User Created Content, cloud computing, data mining, distance learning, and transformative uses by, for instance, documentary filmmakers. Several of these problem areas have given rise to court proceedings with varying outcomes. The interpretation given by courts to existing exceptions and limitations - such as the quotation right, the exception for transient and incidental copying, the private copying exception, and the incidental use exception - is usually too narrow to respond to new technological developments, new developments in the creation process, or new commercialisation models. These types of uses generally do not ‘fit’ the narrowly defined exceptions and limitations and therefore lack legal basis. The same is true for things not yet invented. Because the law is not flexible in itself, courts have increasingly found inventive ways to create legal space for uses that are not covered by the exhaustive list of exceptions. In these cases flexibility with specific evaluation criteria could have been more satisfactory from a legal perspective. Flexibility could be obtained by introducing an open norm in the copyright system. This report defines such an open norm for the purpose of analysing the effects of more flexibility in copyright law. The norm has two main properties. First, it would coexist with the exhaustive list of exceptions and limitations in the current Dutch Copyright Act. Second, a use of a work would only benefit from the open norm if it passes the so-called three-step test, which takes the interests of the author or right holder into account. The first category of economic effects of introducing an open norm is that for some known uses that otherwise require licensing, the open norm would allow unlicensed use. Thispotentially reduces the reward to the creator of a work and therefore decreases the incentive to create. By contrast, it is also likely to reduce the creator’s costs of using another work as an input when producing a new work, and therefore to increase the incentive to create. It is difficult to predict which of these two opposing effects ultimately turns the scale in specific markets. Traditional creators generally worry about the negative effect on their reward and seem to believe that the first effect dominates. For businesses that use large numbers of protected works as an input for their services, such as Google, the opposite is true. They emphasise the benefits of reduced input costs and are likely to improve their legal position with an open norm. Collective rights management organisations in turn fear that their bargaining power vis-à -vis users like UCC-platforms, such as YouTube, would suffer from an open norm. However, given the design of the open norm, it is unlikely that rewards for creators are significantly affected. The application of the open norm by the courts tests for adverse effects on the business model of the rights holder (the previously mentioned three-step test). In case of severe adverse effects on the rights holder, the open norm does not apply. The shift in bargaining power from rights holders to user (platforms) is limited to cases that are currently licensed and where parties are sufficiently confident that the use benefits from the open norm. The second category of economic effects of introducing an open norm is that the legal delineation between infringement and permissible use becomes capable of accommodating developments in technology and society. This enables entrepreneurs to develop new products and services that rely on currently unforeseen use of protected material. On the downside, flexibility may reduce legal certainty in the short run, until jurisprudence on the practice of flexible copyright has developed. The countries that have recently introduced an open norm in their copyright laws have not produced any ex-ante or ex-post studies on the magnitude of these economic effects. The case study of fair use in Israel shows that the change may decrease legal certainty in the short run (as case law needs time to develop), but improve legal certainty in the longer run, as the legal position of acts that do not ‘fit’ a rigid system with an exhaustive list of static exceptions is being clarified. In sum, the main effects of introducing an open norm seem to be of a legal nature: it changes the legal position of some businesses and therefore affects the costs these businesses make to comply with copyright. ‘Tomorrow’s inventions’ are likely to be facilitated by an open norm. Since most businesses seem currently not chilled by the lack of flexibility, the effect on products and services available in the market is likely to be secondary to the legal effects
Solubilization of green plant thylakoid membranes with n-dodecyl-α,D-maltoside. Implications for the structural organization of the Photosystem II, Photosystem I, ATP synthase and cytochrome b6f complexes
Comparison of negative and positive ion electrospray tandem mass spectrometry for the liquid chromatography tandem mass spectrometry analysis of oxidized deoxynucleosides
AbstractOxidized deoxynucleosides are widely used as biomarkers for DNA oxidation and oxidative stress assessment. Although gas chromatography mass spectrometry is widely used for the measurement of multiple DNA lesions, this approach requires complex sample preparation contributing to possible artifactual oxidation. To address these issues, a high performance liquid chromatography (HPLC)-tandem mass spectrometric (LC-MS/MS) method was developed to measure 8-hydroxy-2′-deoxyguanosine (8-OH-dG), 8-hydroxy-2′-deoxyadenosine (8-OH-dA), 2-hydroxy-2′-deoxyadenosine (2-OH-dA), thymidine glycol (TG), and 5-hydroxymethyl-2′-deoxyuridine (HMDU) in DNA samples with fast sample preparation. In order to selectively monitor the product ions of these precursors with optimum sensitivity for use during quantitative LC-MS/MS analysis, unique and abundant fragment ions had to be identified during MS/MS with collision-induced dissociation (CID). Positive and negative ion electrospray tandem mass spectra with CID were compared for the analysis of these five oxidized deoxynucleosides. The most abundant fragment ions were usually formed by cleavage of the glycosidic bond in both positive and negative ion modes. However, in the negative ion electrospray tandem mass spectra of 8-OH-dG, 2-OH-dA, and 8-OH-dA, cleavage of two bonds within the sugar ring produced abundant S1 type ions with loss of a neutral molecule weighing 90 u, [M − H − 90]−. The signal-to-noise ratio was similar for negative and positive ion electrospray MS/MS except in the case of thymidine glycol where the signal-to-noise was 100 times greater in negative ionization mode. Therefore, negative ion electrospray tandem mass spectrometry with CID would be preferred to positive ion mode for the analysis of sets of oxidized deoxynucleosides that include thymidine glycol. Investigation of the fragmentation pathways indicated some new general rules for the fragmentation of negatively charged oxidized nucleosides. When purine nucleosides contain a hydroxyl group in the C8 position, an S1 type product ion will dominate the product ions due to a six-membered ring hydrogen transfer process. Finally, a new type of fragment ion formed by elimination of a neutral molecule weighing 48 (CO2H4) from the sugar moiety was observed for all three oxidized purine nucleosides
Synergy of Fiber Surface Chemistry and Flow Multi PhaseTranscrystallization in Fiber Reinforced Thermoplastics
Fiber reinforced polymer composites are largely employed for their improved strengthwith respect to unfilled matrices. Considering semi crystalline materials under relevant processingconditions, the applied pressure and flow induce shear stresses at the fiber polymer interface.These stresses may strongly enhance the nucleation ability of the fiber surface with respect to thequiescent case. It is thus possible to assume that the fiber features are no longer of importance andthat crystallization is dominated by the effect of flow. However, by making use of an advancedexperimental technique, i.e., polarization modulated synchrotron infrared microspectroscopy PM SIRMS , we are able to show that the opposite is true for the industrially relevant case of isotacticpolypropylene iPP . With PM SIRMS, the local chain orientation is measured with micron size spatialresolution. This orientation can be related to the polymer nucleation density along the fiber surface.For various combinations of an iPP matrix and fiber, the degree of orientation in the cylindricallayer that develops during flow correlates well with the differences in nucleation density found inquiescent conditions. This result shows that the morphological development during processing ofpolymer composites is not solely determined by the flow field, nor by the nucleating ability of the fibersurface alone, but rather by a synergistic combination of the two. In addition, using finite elementmodeling, it is demonstrated that, under the experimentally applied flow conditions, the interphasestructure formation is mostly dominated by the rheological characteristics of the material rather thanperturbations in experimental conditions, such as shear rate, layer thickness, and temperature. Thisonce again highlights the importance of matrix filler interplay during flow and, thus, of materialselection in the design of hybrid and lightweight composite technologie
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